Wicking instrument for LASIK surgery

ABSTRACT

An apparatus and method are provided for use in removing liquid from under a corneal flap generated during LASIK surgery. The apparatus comprises a handle, a sickle-shaped end coupled to the handle, the sickle-shaped end having a concave and a convex portion, and a sponge coupled with the concave portion of the sickle-shaped end, extending along the convex portion thereof, and being shaped substantially similarly to the sickle-shaped end. The sickle-shaped end extends from approximately 180° to 270°, or any other desired part of a circle and may have sponge on one or both sides thereof. The radius of the sickle-shaped end is the same or slightly larger than the diameter of a corneal flap generated during LASIK surgery so that when the apparatus is placed adjacent the cornea of a patient about the corneal flap, liquid is wicked from thereunder without requiring any contact with the corneal flap.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 09/419,130filed Oct. 5, 1999, now U.S. Pat. No. 6,514,223.

BACKGROUND OF THE INVENTION

Refractive eye surgery is a general term for a surgical procedureintended to improve or correct the focus of a patient's eyes by changingthe shape of the eye, thereby changing the optics by which the eye seesvarious images. While surgeries reshaping various portions of apatient's eye have been employed for some time, most recently,refractive eye surgery has involved reshaping the cornea of a patient'seye.

The cornea is the clear, front surface of the eye of a person whichrefracts, or bends light as it enters the eye. This light that is bentby the cornea is focused on the retina of the eye. The retina is a layerof light-sensitive cells that lines the back of the eye. The retinaconverts light rays incident thereon into electrical impulses. Theseelectrical impulses are sent through the optic nerve of the person tohis or her brain. In the brain, these impulses are interpreted asimages. If images received by the eye and refracted or bent by thecornea are not properly focused on the retina, the eye is said to have arefractive error. Myopia (near-sightedness), hyperopia(far-sightedness), and astigmatism (distortion at both near and fardistances) are terms used to describe the refractive error of an eye.These refractive errors are the result of various irregular cornealcurvatures, lens curvatures, or axial eye lengths that prevent imagesfrom being focused to a single point on the eye's retina.

In performing refractive eye surgery, an excimer laser (excited dimer)may be used to reshape the cornea, thereby enabling the cornea toproperly focus received light on the retina. The excimer laser interactswith the corneal tissue of the eye utilizing a laser-tissue interactioncalled photoablation. In photoablation, ultraviolet laser pulsesprecisely etch the cornea by uncoupling various intermolecular bondsthereof, thereby removing a submicron layer of cornea under highlycontrolled conditions. Because there is a relative absence of thermalinjury to the corneal tissue during this procedure, the corneal cellscan be ablated without opacifying (rendering so that light cannot passtherethrough) adjacent tissue. Such opacification might result in theinability to see through the opacified tissue of the eye. By carefullycontrolling the number of pulses of the ultraviolet laser, and thediameter and location of each pulse, the corneal tissue of a patient canbe resculpted as necessary in order to improve the patient's vision.

An early procedure using such an excimer laser is called PRK(photorefractive keratectomy). In this procedure, the outer surface of apatient's eye is acted upon by the laser to change the shape of thecornea. While this procedure has been quite effective in improving apatient's vision, the procedure has a number of disadvantages. Theseinclude a relatively long recovery time after the procedure, discomfortfor the patient during and after the procedure, possible infection ofthe eye after procedure, the requirement for a rigid post-operativeregimen, and a limit in the type of refractive corrections that can beperformed.

In an attempt to improve on the PRK procedure, a new procedure entitledLASIK, or laser-assisted in-situ keratomileusis has been developedutilizing the excimer laser for refractive surgery. This variation ofthe original PRK procedure has become widely accepted and is practicedby ophthalmologists worldwide. This procedure has a number of advantagesover traditional PRK, including a faster recovery time, less discomfortfor the patient, a lower risk of infection, a more convenientpost-operative regimen, and the greatest range of refractive correctionpossibilities. As a result, the LASIK procedure has surpassed PRK in thenumber of annual procedures performed.

The LASIK procedure involves the use of the above-noted excimer laserfor resculpting corneal tissue within the body of the cornea, known asthe corneal stromal bed, as opposed to resculpting the surface andstroma of the cornea, as performed in the PRK procedure. In LASIK,unlike PRK, a corneal flap is created by slicing the cornea along itslamellar plane with an instrument called a microkeratome. The flapformed by this slicing, the outermost 20 percent of the thickness of thecornea, is lifted and reflected to the side. A connecting portion, orhinge between the flap and the eye remains so that the flap does notbecome completely disconnected from the remainder of the cornea. Thereflecting of this flap serves to expose the corneal stroma, or middlelayer of the corneal anatomy, to the computer-controlled laser pulseswhich reshape the corneal curvature. The excimer laser then reshapes themiddle layer of the cornea.

After the corneal stromal bed is acted upon by the excimer laser, theflap is placed back in its original position on the cornea. Thereplacement of the flap provides coverage and protection for theinternal surface of the cornea acted upon by the excimer laser. Afterthe flap has been replaced, a steady stream of fluid is introduced underthe flap, thereby momentarily “floating” the flap relative to theremainder of the cornea to eliminate any small amounts of debris thatmay be present between the flap and the remainder of the cornea as aresult of the LASIK procedure. After a sufficient amount of fluid hasbeen introduced, a milking or “squeegee” procedure follows for removingthis excess fluid from beneath the flap margins, or “gutters”. Finally,the flap gutters are further dried so as to seal and adhere the cornealflap to the remainder of the cornea. This drying is conventionallyperformed by applying merocel (PVA) sponge spears, one point at a time,to various positions around the circumferential edge of the cornealflap.

After the LASIK procedure, many patients' vision returns to anuncorrected 20/20, and occasionally even better with excellent visualimprovement over the first 24 hours. Occasionally, results are lessimpressive than expected. If there is no debris in the flap-stromainterface, and no intralamellar microfolds or wrinkles (striae) in theflap, the likelihood for an excellent result increases dramatically.Thus, a pristine initial postoperative appearance typically leads tofaster visual recovery, better visual results, and a decreased chance ofsignificant inflammatory reaction. However, the introduction of anydebris or striae under or in the flap will require the flap to be lifteda second time to avoid inflammation of the eye, generation of anirregular astigmatism, or any other compromised results. The degree offlap manipulation, or the number of times the flap must be touched,moved or contacted is directly related to the generation of flap striae.Thus, the less the flap needs to be touched, the less the chance ofstriae being generated.

A critical step in the procedure, and a step which if performed properlygreatly reduces the occurrence of striae, involves the replacement ofthe flap and subsequent flap and corneal stroma irrigation, drying ofthe space between the flap and the corneal stroma and adhesion of theflap to the corneal stroma bed. As noted above, after completion of theLASIK laser treatment, surgeons advocate irrigating between the flap andthe corneal stromal bed very thoroughly at the flap-stroma interface toeliminate any debris therefrom. The introduction of this irrigatingsolution creates a lake of fluid, as noted above, floating the flapmomentarily, so that any debris is removed therefrom. This fluid and thehinge remaining between the flap and the corneal stroma bed also guidesthe flap back into proper position. After being properly replaced, asalso noted above, the next step in the procedure involves removing theliquid from the interface between the flap and the stroma of the cornea.This process is performed by milking or squeegeeing of this fluid with amoist merocel (PVA) sponge over the surface or epithelium of the corneaand corneal flap. A sponge is placed in the middle of the cornea, and ispassed over the corneal flap to the outer surface thereof to force theliquid from beneath the flap. This process is performed a plurality oftimes as necessary to remove fluid from beneath the flap. Othervariations which perform a similar function of applying pressure to theflap surface to remove fluid from under the flap include the use of aflap applanator or the use of a corneal compressor, as is well-known inthe art.

However, it is this step involving contact with the surface of the flapthat is fraught with danger. First, any of the sponges or instrumentsthat are dragged across the corneal epithelium may create a cornealabrasion, and sometimes may even puncture the corneal epitheliumentirely. The result of such an abrasion or puncture of the cornea ispainful, and the eye may be prone to infection. Additionally, such anabrasion can produce unpredictable visual outcomes which are lesssuccessful than desired. In addition, whether a sponge or otherinstruments are used in this procedure, the milking process involvesdepressing the delicate corneal flap, dramatically increasing thechances of generating striae therein, or other problems with the flap,thereby further adversely affecting refractive outcome.

After the milking or squeegee process has been completed, further dryingis typically required circumferentially around the flap margins toencourage adhesion of the flap to the underlying stroma of the cornea.This is customarily achieved by gently applying a dry merocel spongespear one point at a time to the entire approximately 270° margincircumference, thereby wicking any residual fluid therefrom. This is atime-consuming, tedious process that involves multiple touches to theflap margin to remove the fluid therefrom. Because of these multipletouches to the flap, damage around the edge surface thereof, or thegeneration of striae therein are possible. Furthermore, the flap mayshift out of alignment before adhesion as a result of these touches,once again reducing the success of the refractive outcome of thesurgery. Therefore, it would be beneficial to provide a method andapparatus for removing excess liquid from under the corneal flap, whilereducing the required level of manipulation of the corneal flap anddirect contact with the corneal flap.

OBJECTS OF THE INVENTION

It is therefore an object of the invention to provide an improved methodand apparatus for wicking fluid from underneath a corneal flap duringthe performance of a LASIK surgery procedure.

Another object of the invention is to provide an improved liquid wickingmethod and apparatus that removes excess liquid from under a cornealflap after LASIK surgery has been performed without coming into directcontact with the corneal flap, and without moving the corneal flap.

A further object of the invention is to provide an improved method andapparatus for insuring proper adhesion between a corneal flap and theremainder of the corneal stroma bed after LASIK surgery has beenperformed by removal of liquid from under the corneal flap until theinterface between the corneal flap and the remainder of the cornea isdry, without making contact with the corneal flap.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specifications and thedrawings.

SUMMARY OF THE INVENTION

A method and apparatus, in accordance with the invention for removingliquid from under a corneal flap replaced after LASIK surgery, isprovided that allows for the removal of this liquid without contactbetween the instrument and the corneal flap. In a first embodiment, theinstrument comprises a handle with a sickle-shaped end formingapproximately 270° of a circle. One face of the sickle-shaped end of theinstrument has a merocel PVA sponge attached thereto and conforming tothe shape of the 270° sickle-shaped end of the instrument. During use,the diameter of sickle-shaped end of the instrument is provided to bethe same or slightly larger than the typical circumference of a cornealflap produced during LASIK surgery. A handle thereof may be provided atany desired angle to the plane of the sickle-shaped end of theinstrument to aid in the manipulation thereof.

After surgery, the sickle-shaped end of the instrument, including themerocel sponge, is placed adjacent to the cornea of a patient to form a270° crescent just slightly larger than outside circumference of thecorneal flap. By capillary action, liquid from under the corneal flap isdrawn into the merocel sponge. In this manner, liquid can be removedfrom under the corneal flap without contacting the corneal flap, therebyimproving results of LASIK surgery.

In an alternative embodiment, rather than having the sponge merelyconform to the sickle-shaped portion of the instrument, extendedportions of the sponge material are provided to extend across a user'sconjunctiva to allow for the removal of excess liquid. More liquid maybe removed and held by the apparatus of this alternative embodiment sothat only one instrument need be used for each eye.

In a further alternative embodiment, rather than including a 270°sickle-shaped end, the instrument of this embodiment includes asemi-circular end of approximately 180°, and is provided with a merocelsponge on either side of the semi-circular instrument substantiallyparallel to the plane thereof. Thus, the sponge on one side of thesemi-circular end of the instrument can be used for removing liquid fromunder one side of the corneal flap, and thereafter the instrument can beflipped over and the sponge on the other side of the semi-circular endof the instrument can be used to remove liquid from the other side ofthe corneal flap.

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, and theapparatus embodying features of construction, combinations of elements,and arrangements of parts that are adapted to effect such steps, all asexemplified in the following detailed disclosure, and the scope of theinvention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention, reference is made tothe following description and accompanying drawings, in which:

FIG. 1 depicts an eye, along with a corneal flap and a corneal flapmargin;

FIG. 2 depicts a wicking instrument constructed in accordance with afirst embodiment of the invention;

FIG. 3 depicts the wicking instrument of FIG. 2 in place around acorneal flap margin;

FIG. 4 depicts a wicking instrument constructed in accordance with asecond embodiment of the invention;

FIG. 5 depicts the wicking instrument of FIG. 4 in position around acorneal flap;

FIG. 6 depicts a wicking instrument constructed in accordance with athird embodiment of the invention;

FIGS. 7A and 7B depict the wicking instrument of FIG. 6 in use onopposite sides of a corneal flap; and

FIG. 8 depicts a wicking instrument constructed in accordance with analternative embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIG. 1, a corneal flap generated through theperformance of LASIK surgery procedure is depicted in reference to apatient's eye. A patient's eye is shown at 100 and a colored irisportion thereof is shown at 110. 120 depicts the patient's pupil. Acorneal flap margin 130 about a corneal flap 150 is depicted as analmost complete circle extending just inside most of the iris coloredportion 110 except for a hinged portion 140. This corneal flap margin isgenerated during LASIK surgery, and hinged portion 140 maintains thecorneal flap portion in contact with the corneal stroma of the cornea110. As noted in the Background and Summary of the Invention, afterperformance of LASIK surgery, this area underneath corneal flap 150 andabove the corneal stroma of cornea 110 is irrigated with a large amountof fluid to remove any debris therefrom and for floating the cornealflap so that it may be properly placed by hinged portion 140.

Referring next to FIG. 2, an apparatus constructed in accordance with afirst embodiment of the invention is depicted, indicated generally at200. Wicking instrument 200 includes a handle portion 210, asickle-shaped portion 220, and a highly absorbent PVA sponge portion 230positioned coextensive with, and coupled to sickle-shaped portion 220.Handle or shaft 210 of the instrument is preferably formed with arounded cross-section, and includes a coarse surface at the terminal endthereof opposite end 220 to improve grip of the instrument. While inFIG. 2 the handle is shown coplanar to the shape of sickle-shaped end220, as is shown in FIG. 8, in an alternative construction it is alsopossible to position the shaft and handle portion 210 of the instrumentat a 45° angle to the plane of the sickle-shaped end 220, or at anyother angle which may be beneficial for improving ease of use of theinstrument. Additionally, this angled handle may be applied to any ofthe embodiments of the invention.

The radius of sickle-shaped portion 220 of the instrument is slightlylarger or equal to the radius of corneal flap 150, taking into accountthe width of sponge portion 230 coupled with end 220. This size allowsfor the maintenance of maximum surface contact with cornea 110, butpositions sponge portion 230 just outside or at corneal flap margin 130.The instrument is preferably constructed of an injected molded sterileplastic, insuring a lightweight, disposable and sterile product. Spongeportion 230 is preferably attached to the inside, or concave edge ofsickle-shaped end 320 of wicking instrument 200, but may be attached inany manner. The sponge continues along one side of sickle-shaped end220, coplanar thereto, and also can extend in a direction perpendicularto the plane of sickle-shaped end 220 outside, and at the convex portionthereof, if desired. The sponge is preferably composed of a highlyabsorbent wicking material such as polyvinyl alcohol (PVA) angled toconform to the shape of the peripheral cornea for maximum surfacecontact with cornea 110 and corneal flap margin 130. However, anymaterial having the features of being synthetic, biocompatible andfiber-free, thereby reducing the chance of eye infections, may be used.Materials such as PVA and the like are preferable to fibrous materialssuch as cotton gauze and cellulose in order to minimize the debris whichmight be trapped under the corneal flap. Additionally, the sponge mustbe soft enough in its dry state to provide some flexibility at its apexwhere corneal contact is initiated. This flexibility will decrease thelikelihood of flap movement upon contact of the cornea with the sponge.

The portion of the sponge at the concave or inside portion ofsickle-shaped end 220 of wicking instrument 200 is preferably formedslightly beveled or otherwise shaped, having approximately a 7.5 mmradius of curvature, in a preferred embodiment, so as to match thenormal corneal profile and to maximize contact of the sponge with thecornea to remove the most fluid from the corneal flap margin. The spongeis also provided at a thickness so as to maximize the absorption ofexcess fluid from under the corneal flap.

As is shown in FIG. 3, during use, wicking instrument 200 is placed sothat sickle-shaped end 220 along with highly absorbent sponge 230 arepositioned concentric with corneal flap margin 130 and as shown has aradius slightly larger than that of the corneal flap margin. The portionof sickle-shaped end 220 that is open (not the complete circle) isplaced adjacent hinge 140 since it is not necessary to wick moisturetherefrom. Upon placement, liquid is wicked from under the corneal flapinto the sponge by capillary action. Through the use of this apparatusand method, it is therefore possible to wick liquid from under cornealflap 130 without making contact with the corneal flap, or squeegeeing orrolling, or risking other movement or abrasion of the corneal flap.

Referring next to FIG. 4, a wicking instrument 400 constructed inaccordance with a second embodiment of the invention is shown.Instrument 400 is provided with a handle 410, and a sickle-shaped end420 similar to those of the first embodiment. A highly absorbent PVAsponge 430 is also provided, and within the concave or inner portion ofsickle-shaped end 420 of instrument 400, is similarly shaped andsituated to the sponge in the first embodiment. However, at the outsideof concave portion of sickle-shaped end 420 of instrument 400, thesponge is provided with elongated portions 432 which conform generallyin shape and size to a patient's eye. Thus, as noted above with respectto the first embodiment, while the portion of the sponge that is totouch a user's eye is beveled or otherwise shaped with curvature tomatch the normal corneal profile of the user's eye adjacent the cornealflap, portions 432 of sponge 430 are similarly contoured and curved tofurther match the curve of a patient's eye. These elongated portions 432greatly increase the liquid-absorbing ability of the instrument.

Referring to FIG. 5, during use instrument 400 is positioned similarlyto instrument 200 of FIG. 3. Thus, the description of FIG. 3 is equallyapplicable to FIG. 5. The only difference being that elongated portions432 allow for extra absorption surfaces for removing liquid from thepatient's eye, insuring that only one instrument need be used for eachprocedure.

Referring next to FIG. 6, a wicking instrument, indicated generally at600, constructed in accordance with a third embodiment of the inventionis shown. In this embodiment, wicking instrument 600 is formed with ahandle portion 610, a semi-circular shaped end 620 with a semi-circularshaped sponge 630 coupled therewith. Rather than the sponge only beingprovided on one surface of the instrument coplanar to the end, as isshown in FIGS. 2 and 4, in this third embodiment, sponge 630 is providedon both the upper and lower surfaces of the semi-circular shaped end620, and coplanar therewith. Thus, as is shown in FIG. 7A, during usesemi-circular end 620 of instrument 600 including sponge 630 is firstplaced adjacent the corneal flap margin so that sponge 630 wicksmoisture from one side of the corneal flap margin. Thereafter, as isshown in FIG. 7B, semi-circular end 620 is flipped over and is placed sothat sponge 630 is positioned adjacent the opposite side of corneal flapmargin 130 from that of FIG. 7A. In this manner, both sides of theinstrument are used in order to wick fluid from under opposite sides ofcorneal flap margin 130. The use of such a semi-circular shaped end maybe beneficial if and when a corneal flap margin generated is of anirregular size or shape, allowing a user performing the wickingoperation with slightly more latitude of movement.

Because this third embodiment must use both sides of the instrument, inthe preferred embodiment, the handle is formed coplanar with thecrescent-shaped instrument head, but may be provided with a slightangle, or a movable, changeable angle if desired.

In yet another alternative embodiment in the invention, it may bepossible to construct the instrument of a light metal or other reusablematerial that may be sterilized. The sponge is removably attachedthereto and is manufactured as a disposable attachment so that only thesponge portion need be replaced after each use.

In accordance with the invention, the uniquely shaped wickinginstruments of the invention described above provide a number ofbenefits. First, the instruments allow the replacement of the riskysqueegee step in the LASIK procedure, and also avoid the need to performmultiple wicking steps. Thus, flap adhesion can be improved bydecreasing the amount of instrument-cornea contact. Therefore, inaccordance with the invention, the currently used pushing or milkingprocess of eliminating fluid from under the corneal flap is replacedwith a gentle pulling or wicking mechanism which removes liquid bycapillary action. The invention permits efficient, evenly distributedegress of fluid from under the corneal flap, thereby simultaneouslyserving to accomplish both the drying and adhesion steps. Moreimportantly, the use of this method and apparatus significantlyminimizes corneal flap manipulation and eliminates contact with thecorneal flap surface entirely. As a result, the risk of the generationof corneal striae and abrasions are minimized accordingly. The use ofthis method apparatus of the invention will therefore lead to improvedrefractive outcomes, increased patient comfort, and healthierpost-surgical corneas.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained and,because certain changes may be made in carrying out the above method andin the constructions set forth without departing from the spirit andscope of the invention, it is intended that all matter contained in theabove description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:
 1. An apparatus for use in removing liquid fromunder a corneal flap generated during LASIK surgery, comprising: ahandle; a sickle-shaped end coupled to said handle, said sickle-shapedend having a concave and a convex portion; and a sponge having a firstand a second side coupled with the concave portion of said sickle-shapedend, and being shaped substantially similarly to said sickle-shaped end,at least one of said sides of said sponge being formed with a concaveradius of curvature so as to maximize contact of the sponge with thecornea.
 2. The apparatus of claim 1, wherein said contour includes aradius of curvature of 7.5 mm.
 3. The apparatus of claim 1, wherein saidsickle-shaped end extends approximately 270%.
 4. The apparatus of claim3, wherein said sponge extends coplanar along one side of saidsickle-shaped end.
 5. The apparatus of claim 4 wherein said spongeextends in a direction perpendicular to the plane of said sickle-shapedend at the convex portion thereof, and is attached thereto.
 6. Theapparatus of claim 4, further comprising at least one elongated portionof said sponge extending coplanar with said sickle-shaped end.
 7. Theapparatus of claim 6, wherein said at least one elongated portion ofsaid sponge is contoured to follow the shape of a conjunctiva.
 8. Theapparatus of claim 3, wherein the radius of said sickle-shaped end isslightly larger than the radius of a corneal flap cut using acorresponding sized blade.
 9. The apparatus of claim 3, wherein saidhandle is formed at an angle relative to the plane of said sickle-shapedend.
 10. The apparatus of claim 9, wherein said angle is 45°.
 11. Theapparatus of claim 1, wherein said sickle-shaped end extendsapproximately 180°.
 12. The apparatus of claim 11, wherein said spongeencircles said sickle-shaped end.
 13. The apparatus of claim 12, whereinsaid sponge is formed with at least one of said sides of said spongehaving a concave contour having a radius of curvature so as to maximizecontact of the sponge with the cornea at two surfaces in the plane ofsaid sickle-shaped end.
 14. The apparatus of claim 11, wherein theradius of said sickle-shaped end is slightly larger than or same as acorneal flap.
 15. The apparatus of claim 11, wherein said handle iscoupled to said sickle-shaped end at an adjustable angle.
 16. Theapparatus of claim 1, wherein said sponge is permanently fixed to saidsickle-shaped end.
 17. The apparatus of claim 1, wherein said sponge isremovably fixed to said sickle-shaped end.
 18. The apparatus of claim 1,wherein said sponge is formed of a synthetic, biocompatible, fiber-freematerial.